From: Sharat Masetty <smasetty@codeaurora.org>
To: Rob Clark <robdclark@gmail.com>
Cc: freedreno <freedreno@lists.freedesktop.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
dri-devel@freedesktop.org,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Georgi Djakov <georgi.djakov@linaro.org>,
Matthias Kaehlcke <mka@chromium.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
saravanak@google.com, Sibi Sankar <sibis@codeaurora.org>,
Rajendra Nayak <rnayak@codeaurora.org>,
Jordan Crouse <jcrouse@codeaurora.org>
Subject: Re: [Freedreno] [PATCH 5/6] drm: msm: a6xx: use dev_pm_opp_set_bw to set DDR bandwidth
Date: Thu, 28 May 2020 16:32:57 +0530 [thread overview]
Message-ID: <46976ed1-d732-cb77-bb0c-c2c6a566b95b@codeaurora.org> (raw)
In-Reply-To: <CAF6AEGvOtgpHMuiw01QgRYGEBB2rp5QOdVMpkTMsi0c-QSSv1Q@mail.gmail.com>
On 5/27/2020 9:08 PM, Rob Clark wrote:
> On Wed, May 27, 2020 at 1:47 AM Sharat Masetty <smasetty@codeaurora.org> wrote:
>> + more folks
>>
>> On 5/18/2020 9:55 PM, Rob Clark wrote:
>>> On Mon, May 18, 2020 at 7:23 AM Jordan Crouse <jcrouse@codeaurora.org> wrote:
>>>> On Thu, May 14, 2020 at 04:24:18PM +0530, Sharat Masetty wrote:
>>>>> This patches replaces the previously used static DDR vote and uses
>>>>> dev_pm_opp_set_bw() to scale GPU->DDR bandwidth along with scaling
>>>>> GPU frequency.
>>>>>
>>>>> Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
>>>>> ---
>>>>> drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 6 +-----
>>>>> 1 file changed, 1 insertion(+), 5 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>>>>> index 2d8124b..79433d3 100644
>>>>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>>>>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>>>>> @@ -141,11 +141,7 @@ void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp)
>>>>>
>>>>> gmu->freq = gmu->gpu_freqs[perf_index];
>>>>>
>>>>> - /*
>>>>> - * Eventually we will want to scale the path vote with the frequency but
>>>>> - * for now leave it at max so that the performance is nominal.
>>>>> - */
>>>>> - icc_set_bw(gpu->icc_path, 0, MBps_to_icc(7216));
>>>>> + dev_pm_opp_set_bw(&gpu->pdev->dev, opp);
>>>>> }
>>>> This adds an implicit requirement that all targets need bandwidth settings
>>>> defined in the OPP or they won't get a bus vote at all. I would prefer that
>>>> there be an default escape valve but if not you'll need to add
>>>> bandwidth values for the sdm845 OPP that target doesn't regress.
>>>>
>>> it looks like we could maybe do something like:
>>>
>>> ret = dev_pm_opp_set_bw(...);
>>> if (ret) {
>>> dev_warn_once(dev, "no bandwidth settings");
>>> icc_set_bw(...);
>>> }
>>>
>>> ?
>>>
>>> BR,
>>> -R
>> There is a bit of an issue here - Looks like its not possible to two icc
>> handles to the same path. Its causing double enumeration of the paths
>> in the icc core and messing up path votes. With [1] Since opp/core
>> already gets a handle to the icc path as part of table add, drm/msm
>> could do either
>>
>> a) Conditionally enumerate gpu->icc_path handle only when pm/opp core
>> has not got the icc path handle. I could use something like [2] to
>> determine if should initialize gpu->icc_path*
>>
>> b) Add peak-opp-configs in 845 dt and mandate all future versions to use
>> this bindings. With this, I can remove gpu->icc_path from msm/drm
>> completely and only rely on opp/core for bw voting.
> The main thing is that we want to make sure newer dtb always works on
> an older kernel without regression.. but, hmm.. I guess the
> interconnects/interconnects-names properties haven't landed yet in
> sdm845.dtsi? Maybe that lets us go with the simpler approach (b).
> Looks like we haven't wired up interconnect for 8916 or 8996 either,
> so probably we can just mandate this for all of them?
I checked all three 845, 820 and 8916 and none of them have the
interconnect configs for GPU. So, I think we are good here. I'll go with
option (b) and re-spin v3. Adding interconnects and opp-peak-kBps
configs for previous chips can be taken up as a separate activity.
Sharat
> If we have landed the interconnect dts hookup for gpu somewhere that
> I'm overlooking, I guess we would have to go with (a) and keep the
> existing interconnects/interconnects-names properties.
>
> BR,
> -R
>
>> [1] - https://lore.kernel.org/patchwork/cover/1240687/
>>
>> [2] - https://patchwork.kernel.org/patch/11527573/
>>
>> Let me know your thoughts
>>
>> Sharat
>>
>>>> Jordan
>>>>
>>>>> unsigned long a6xx_gmu_get_freq(struct msm_gpu *gpu)
>>>>> --
>>>>> 2.7.4
>>>>>
>>>> --
>>>> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
>>>> a Linux Foundation Collaborative Project
>>>> _______________________________________________
>>>> Freedreno mailing list
>>>> Freedreno@lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/freedreno
next prev parent reply other threads:[~2020-05-28 11:03 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-14 10:54 [PATCH 0/6] Add support for GPU DDR BW scaling Sharat Masetty
2020-05-14 10:54 ` [PATCH 1/6] arm64: dts: qcom: sc7180: Add interconnect bindings for GPU Sharat Masetty
2020-05-14 23:37 ` Matthias Kaehlcke
2020-05-14 10:54 ` [PATCH 2/6] arm64: dts: qcom: sc7180: Add opp-peak-kBps to GPU opp Sharat Masetty
2020-05-14 23:45 ` Matthias Kaehlcke
2020-05-14 10:54 ` [PATCH 3/6] OPP: Add and export helper to set bandwidth Sharat Masetty
2020-05-15 0:32 ` Matthias Kaehlcke
2020-05-14 10:54 ` [PATCH 4/6] drm: msm: a6xx: send opp instead of a frequency Sharat Masetty
2020-05-15 0:39 ` Matthias Kaehlcke
2020-05-15 0:58 ` Matthias Kaehlcke
2020-05-14 10:54 ` [PATCH 5/6] drm: msm: a6xx: use dev_pm_opp_set_bw to set DDR bandwidth Sharat Masetty
2020-05-15 1:05 ` Matthias Kaehlcke
2020-05-18 14:23 ` Jordan Crouse
2020-05-18 16:25 ` [Freedreno] " Rob Clark
2020-05-27 8:47 ` Sharat Masetty
2020-05-27 15:38 ` Rob Clark
2020-05-27 17:31 ` Saravana Kannan
2020-05-27 20:41 ` Sibi Sankar
2020-05-27 20:51 ` Jordan Crouse
2020-05-28 11:02 ` Sharat Masetty [this message]
2020-05-14 10:54 ` [PATCH 6/6] dt-bindings: drm/msm/gpu: Document gpu opp table Sharat Masetty
2020-05-28 15:14 ` Rob Herring
2020-05-14 23:56 ` [PATCH 0/6] Add support for GPU DDR BW scaling Matthias Kaehlcke
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